The application claims priority of Korean Patent Application Serial No. 10-2002-0026839 filed on May 15, 2002.
1. Field of Invention
The present invention relates to a microstrip dual band antenna, and more particularly, the present invention relates to a microstrip dual band antenna which can achieve in the industrial, scientific and medical (ISM) band a return loss and a voltage standing wave ratio (VSWR) appropriate to a communication terminal, accomplish a satisfactory radiation pattern, be minimized in its size, and be installed on various radio communication equipment in a miniaturized state.
2. Background of the Invention
These days, with miniaturization of portable mobile communication terminals, internal mounting type antennas have been disclosed in the art. Further, as various communication services are rendered, in order to ensure high communication quality, microchip antennas, which are small-sized, lightweight and capable of overcoming disadvantages of external mounting type antennas, have been developed. Among the microchip antennas, a dual band antenna is highlighted since it can satisfy several kinds of services in an integrated manner.
However, in the conventional art, a drawback exists in that the microchip antenna cannot properly solve problems associated with miniaturization and design of a communication terminal, and it is inherently difficult to expand a bandwidth in the dual band antenna. In particular, since most of the conventional antennas are externally mounted to the communication terminal, impedance matching circuits are employed, and therefore, the number of processes and a manufacturing cost are increased.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a microstrip dual band antenna which can achieve in the ISM band a return loss and a VSWR appropriate to a communication terminal, and accomplish a satisfactory radiation pattern, in a manner such that it can be installed on various radio communication equipment in a miniaturized state.
In order to achieve the above object, according to the present invention, there is provided a microstrip dual band antenna comprising: a feeder hole defined in a widthwise middle portion adjacent to one end of a dielectric body which is formed in the shape of a quadrangular prism; a radiation patch line formed on an upper surface and on a portion of a lower surface of the dielectric body, in a manner such that it is placed around the feeder hole, extends through a first predetermined distance toward the other end of the dielectric body while having a first width corresponding to a diameter of the feeder hole, and extends through a second predetermined distance while surrounding the other end of the dielectric body and having a second width corresponding to a width of the dielectric body; a ground line formed on the lower surface of the dielectric body to be separated from the radiation patch line, in a manner such that it extends toward one end of the dielectric body while having the second width corresponding to the width of the dielectric body; a pair of strip lines formed on the lower surface of the dielectric body in a manner such that each of them substantially defines an L-shaped configuration and extends from a position separated from the feeder hole toward the other end of the dielectric body; and a pair of connection holes defined in the dielectric body at both sides of the feeder hole, respectively, and plated with suitable material.